I just downloaded iTunes 10.5 and tried to install it on my Windows 7 64 bit machine. What I got was an error message that said:

There is a problem with this WIndows Installer package. A program required for this install to complete could not be run. Contact your support personnel or package vendor.

The fix that allowed 10.5 to install correctly was very simple. Simply go to Control Panel > Uninstall a Program. Right-click on “Apple Software Update” and choose “Repair.” After that, iTunes 10.5 (x64) should install with no problems at all. Apparently the Apple Updater can get messed up and cause the new version not to install. Imagine that.

Wont work if the apple updater was uninstalled. Maybe if apple didn’t hijack the pc, there wouldn’t be this problem. Obviously you are an apple lover. I only use itunes because you have to if you have an ipad.

I’m not an Apple lover: I used a Macbook for development for about 4 years but decided I missed the openness (and affordability) of the PC. I really don’t like iTunes at all, but it’s a necessary evil for a lot of iDevice folks. Given that, any possible fixes for stuff that goes wrong are probably useful to a lot of people.